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06-17-2011, 12:01 PM   #16
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I think if you wanted to crop it that tightly from the original picture, then you should have stood closer and the subject would have filled more of the picture and you wouldn't have had as much noise, alot more detail in the subject ect. Its one thing to pixel peep, but another to pixel peep and then crop the picture by over 50% and still expect it to have the greatest resolution. If you print that picture in it's original form you wouldn't notice any noise until you went above a 8x10 print anyhow. I have a 24 inch monitor and the picture full screen and I still see little to no noise. You would have to zoom into till the subject is the only thing in the picture to really notice the noise. Also its partly your post processing and it being jpg.

It doesn't help that the subject is dark, and in front of quite a bright background. I think had the subject rotate 45 degrees to her left she would have caught more might and the exposure would have been better.

Anyhow while I was fiddling around with the picture looking at the noise and I thought I'd send it back to you in case you like the post processing I did. I think you took a wonderful picture, and makes me jealous, its been all but rain here for the last week and a half lol. http://stevenkovickart.com/pentaxforums/K5_S2896.jpg

P.S. it looks like you have some sensor dust now that I look at the sky more closely.


Last edited by Dr_who; 06-17-2011 at 12:33 PM. Reason: added P.S.
06-17-2011, 12:25 PM   #17
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It's also worth a quick note that if you shoot raw, some sharpening is necessary to achieve optimal sharpness. This has to do with the nature of AA filters and Bayer sensors.
06-17-2011, 02:28 PM   #18
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QuoteOriginally posted by jstevewhite Quote
It's also worth a quick note that if you shoot raw, some sharpening is necessary to achieve optimal sharpness. This has to do with the nature of AA filters and Bayer sensors.
To continue on this a little: on a bayer sensor (all camera sensors of today except foveon and a few Fuji sensors that have different color arrays) every other sensel is green, and every forth is blue or red, respectively. That means that with out of your 16 MP, 8 are green, 4 are blue and 4 are red. The final output (the jpeg) is a 16 MP where each pixel has a green, blue and red value. In other words, for every other pixel, the green information is interpolated, and for three out of four pixels the blue and red information respectively is interpolated. Therefore, you should never expect perfect sharpness at the pixel level when using a bayer sensor (which again are used by almost all manufacturers - Pentax, Sony, CaNikon, Samsung, Panasonic and so on). If you see images that have such sharpness, it comes from the sharpness algorithms "guessing" that that is how it should be - and they usually guess pretty well for simple, large structures, like lines i a picture.
06-17-2011, 05:15 PM   #19
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QuoteOriginally posted by JeffJS Quote
...

This is a shot that was severely underexposed. Pushed 4 stops and a good amount of noise reduction but as you can see from the full size image, it is far from being sharp (anymore).

http://farm5.static.flickr.com/4057/5151802497_1deab6ced0_o.jpg
It's not sharp at full size, but I still see it as being sharper and cleaner than my photo, even when pushed less than 4 stops.


QuoteOriginally posted by JeffJS Quote
...

Back to the image, at 28mm it's about what I would expect given experience. I can see the details in her face and I can almost read the label on the water bottle she is carrying.

I suppose I should feel relieved. The comments here MAY help explain why some of my shots with the 18-55WR lens at 18mm/f3.5 appear sharp on near subjects, and quite fuzzy on more distant ones, even though one would expect the larger DOF at the greater distance to mask focusing errors. I may try to explore this in another post.

06-17-2011, 05:26 PM   #20
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QuoteOriginally posted by Dr_who Quote
I think if you wanted to crop it that tightly from the original picture, then you should have stood closer and the subject would have filled more of the picture and you wouldn't have had as much noise, alot more detail in the subject ect. Its one thing to pixel peep, but another to pixel peep and then crop the picture by over 50% and still expect it to have the greatest resolution. If you print that picture in it's original form you wouldn't notice any noise until you went above a 8x10 print anyhow. I have a 24 inch monitor and the picture full screen and I still see little to no noise. You would have to zoom into till the subject is the only thing in the picture to really notice the noise. Also its partly your post processing and it being jpg.

It doesn't help that the subject is dark, and in front of quite a bright background. I think had the subject rotate 45 degrees to her left she would have caught more might and the exposure would have been better.
Points taken.

QuoteOriginally posted by Dr_who Quote
Anyhow while I was fiddling around with the picture looking at the noise and I thought I'd send it back to you in case you like the post processing I did. I think you took a wonderful picture, and makes me jealous, its been all but rain here for the last week and a half lol. http://stevenkovickart.com/pentaxforums/K5_S2896.jpg
I do like the PP, thank you. I sometimes induce similar colours in my own processing. As to the weather, we had almost nonstop cloud and drizzle during a week in Milan, the only notable exception being our excursion to Venice, and then the clouds came just as we started heading back to the train for our return. Talk about luck.

QuoteOriginally posted by Dr_who Quote
P.S. it looks like you have some sensor dust now that I look at the sky more closely.
I haven't paid any attention to this, so I don't know how to identify the dust. Is it what resembles random noise, noticeable in the top left corner? Or?
06-17-2011, 05:30 PM   #21
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You seem to do it ALL wrong, but that is just INexperience. Give it some more time and effort (not money hopefuly hhhh )

You have an exposure lock button, but maybe the best is to start shooting M-mode only + green button until you are OK with them.

Pentax K-5 has THE BEST ergonomy on the universe so you will soon feel like fish in water

Last edited by dreamfoto; 06-17-2011 at 05:44 PM.
06-17-2011, 05:46 PM   #22
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QuoteOriginally posted by jstevewhite Quote
It's also worth a quick note that if you shoot raw, some sharpening is necessary to achieve optimal sharpness. This has to do with the nature of AA filters and Bayer sensors.
QuoteOriginally posted by hjb981 Quote
To continue on this a little: on a bayer sensor (all camera sensors of today except foveon and a few Fuji sensors that have different color arrays) every other sensel is green, and every forth is blue or red, respectively. That means that with out of your 16 MP, 8 are green, 4 are blue and 4 are red. The final output (the jpeg) is a 16 MP where each pixel has a green, blue and red value. In other words, for every other pixel, the green information is interpolated, and for three out of four pixels the blue and red information respectively is interpolated. Therefore, you should never expect perfect sharpness at the pixel level when using a bayer sensor (which again are used by almost all manufacturers - Pentax, Sony, CaNikon, Samsung, Panasonic and so on). If you see images that have such sharpness, it comes from the sharpness algorithms "guessing" that that is how it should be - and they usually guess pretty well for simple, large structures, like lines i a picture.
It was not my intention to pixel-peep, and I'm not striving here for super-sharpness. It's just that I have too many photos that are totally out of focus (I'd already posted some samples awhile back). Having done some tests with various AF Adjustment settings, I've managed to come up with some values that provide reasonable AF consistency under specific indoor lighting. I was dismayed when I saw the variability in my outdoor shots, especially given the small apertures used, where I'd expect the larger DOF to mask the AF errors. However, after reading the comments here, I am able to conclude that what I'm getting is par for the course.
06-17-2011, 05:55 PM   #23
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bxf,

did you reprogram the shutter release button? I did deactive the auto-focus on half-pressed SR button and focus only using the AF button.

This allows me to focus and redo the composition later without having to focus again.

Also to obtain good sharpness you need good light. In the original image a fill-flash seems like a good idea too.

06-17-2011, 05:59 PM   #24
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Barrel distortion is visible, but maybe this is ok for such wide angle - which lens is that? 18-55 kit?

How about lens correction - barrel distortion correction?
06-17-2011, 06:35 PM   #25
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QuoteOriginally posted by dreamfoto Quote
You seem to do it ALL wrong, but that is just INexperience. Give it some more time and effort (not money hopefuly hhhh )

You have an exposure lock button, but maybe the best is to start shooting M-mode only + green button until you are OK with them.

Pentax K-5 has THE BEST ergonomy on the universe so you will soon feel like fish in water
Quite apart from the fact that we're talking about a simple snapshot, somehow I was doing it ALL less wrong with my K20D, where I was getting fewer fuzzy photos than I'm getting with the K-5, using the same lens.

QuoteOriginally posted by dreamfoto Quote
bxf,

did you reprogram the shutter release button? I did deactive the auto-focus on half-pressed SR button and focus only using the AF button.

This allows me to focus and redo the composition later without having to focus again.

Also to obtain good sharpness you need good light. In the original image a fill-flash seems like a good idea too.
Do you believe the camera is focusing on something other than the intended subject? If not, the button assignment is irrelevant. At this combination of focal length, aperture, and subject distance, the subject will definitely remain within the DOF after recomposing.

QuoteOriginally posted by dreamfoto Quote
Barrel distortion is visible, but maybe this is ok for such wide angle - which lens is that? 18-55 kit?

How about lens correction - barrel distortion correction?
Already indicated in the original post: Tamron 28-75 f2.8. And yes, I do perform lens correction when I process my images. The one provided here was intentionally left unprocessed.

Last edited by bxf; 06-18-2011 at 02:10 PM. Reason: lost a phrase
06-18-2011, 01:04 AM   #26
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QuoteOriginally posted by bxf Quote

I haven't paid any attention to this, so I don't know how to identify the dust. Is it what resembles random noise, noticeable in the top left corner? Or?
I renamed the picture with the dust spots circled. Its a little hard to see as the noise reduction and post processing has softened it a little. And its nearly impossible to see in the bottom half of the photo as its so busy with detail. The best thing to do is take a picture of only the blue sky at F18 and it becomes alot easier to find.

http://stevenkovickart.com/pentaxforums/K5_S2896b.jpg

here is a more better example in a random other photo so you have an idea of what your looking for. Real-life dangers of dust-bunnies. photo - Nicholas R. photos at pbase.com
06-18-2011, 02:47 AM   #27
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Maybe I missed the point here. Or maybe I didn't ???

But why do you press the SR button if you dont like the result?

There's the the Live View, you can zoom it and see exactly what you have in focus and how sharp it will look. Did the image look good before you pressed the SR? Why not? Or what went wrong after in case if it did.

BTW Are you sure the Tamron is well calibrated and focusing properly? Does it have stains or fungus or some oil etc, does the apperture work as it should? Check that in Live View (keep in mind the focusing may use different technique there), Check with another lens too.

Do you have proper capture settings? Have you checked the histogram for exposure problems? For this image the speed should be at least 1/80sec preferably 1/200 and faster. Use tripod if needed. Do you have proper aperture setting? F22 and F16 should do for some lenses and maybe not for others? Try experimenting with the lens and see where you get performance. Some lenses have very poor performance at wide apertures too. Keep your lens around the sweet spot... If you are using zoom lens keep it around the sweet zoom range, typically not near the extremes.

How are the camera settings? Can you reset the default settings to be sure that you have not modified something by mistake.

For sharp image you need good light. Check under good conditions if you get sharp images. You need lights with direction and no color for that. Do you use lens hood? In general you should. In some cases to improve contrast you can put a polarizer on your lens. But in other is can actually make things worse

Start with a simple scene. No need to have sea, sky infinity background with lots of details and foreground objects at the same time. With a DSLR you can start with simple composition and add complexity to the scenes later.

etc etc
06-18-2011, 06:55 AM   #28
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f 9.5 corresponds to an airy disk diameter of about 12.75 micrometers. The pixel spacing on the K-5 is 4.8 micrometers.

At 100% display each diffraction spot is occupying at least 2-1/2 display pixels therefore it looks soft. You are viewing it from about 1/2 meter I suppose. View it from a couple of meters back and it will look much better - or display it at about 40%.

The problem is that "100% display" implicitly assumes resolution is limited by the sensor's pixel pitch but in this case the limitation is likely the diffraction spot size because of the high f-stop relative to the camera's pixel pitch.

Last edited by newarts; 06-18-2011 at 10:38 AM.
06-18-2011, 07:08 AM   #29
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QuoteQuote:
Quite apart from the fact that we're talking about a simple snapshot, somehow I was doing it ALL less wrong with my K20D, where I was getting fewer fuzzy photos than I'm getting with the K-5, using the same lens.
Hmmm... the pixel spacing on the K20D is only a little more than the K-5 so unless they have differing AA filter strengths one would expect about the same diffraction softening at f:9.5

F:diffraction.onset = Pixel.Pitch/(2.44wavelength) ~ 3(sensor.width.mm/sensor.width.pixels)/4

Roughly speaking you can expect to see diffraction softening at 100% when the f stop is greater than the sensor's pixel pitch in micrometers.

Last edited by newarts; 06-18-2011 at 10:40 AM.
06-18-2011, 01:48 PM   #30
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QuoteOriginally posted by Dr_who Quote
I renamed the picture with the dust spots circled. Its a little hard to see as the noise reduction and post processing has softened it a little. And its nearly impossible to see in the bottom half of the photo as its so busy with detail. The best thing to do is take a picture of only the blue sky at F18 and it becomes alot easier to find.

http://stevenkovickart.com/pentaxforums/K5_S2896b.jpg

here is a more better example in a random other photo so you have an idea of what your looking for. Real-life dangers of dust-bunnies. photo - Nicholas R. photos at pbase.com
Sorry for the delayed response, but I've spent all this time scrutinizing the circled areas, trying to locate the dust. My screen and my glasses have more visible spots Just kidding. I do see something but very faint, and I never would have thought anything of it. The spots in the link you provided are certainly more obvious. I'll try Dust Removal, and keep my eyes open. Thanks.
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